Fine mapping of and , two minor QTL conferring grain size and weight in rice.

UNLABELLED

Rice grain size is a key determinant of both grain yield and quality. In this study, we conducted QTL mapping on grain size using a recombinant inbred line (RIL) population derived from a cross between variety Beilu130 (BL130) and variety Jin23B (J23B). A total of twenty-two QTL related to grain length (GL), grain width (GW), grain length-to-width ratio (LWR), grain thickness (GT), and thousand grain weight (TGW) were detected under two environments, and 14 of them were repeatedly detected. Two minor QTL, and , were validated and further delimited to regions of 631 kb and 272 kb, respectively. Parental sequence comparison of genes expressed in inflorescence in corresponding candidate regions identified frameshifts in the exons of and , both of which encode protein phosphatase 2C-containing protein, and , which encodes a BIM2 protein. Scanning electron microscopy (SEM) analysis revealed that the increase of cell size rather than cell number caused the differences in grain size between NILs of and . Quantitative RT-PCR analysis showed that the expression levels of , , , , , and were significantly different in both NILs and NILs. Our results lay the foundation for the cloning of and , and provide genetic materials for the improvement of rice yield and quality.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11032-022-01328-2.